Thank you BD139!
Here's the Time/Division switch after it was thoroughly cleaned, and btw, how that big .22uf capacitor (C135D) split in service, is beyond me. The casing appears to be rock-hard epoxy.
The small 5% Wima capacitor was what I could find in my stash to replace the smaller 2200pf cap (C135B), none the less, all of the resistors and capacitors for this switch measure less than 1% tolerance. Heck, 99% of all of the parts I put in this scope are less than 1%.
I just checked Digi-Key, and they have a long-lead 2200pf PP cap that I may throw into this week's order.
Anyway, I'm just having fun!
Whoah! scratch that. I was concerned about the short leads on that Wima cap. It pays to take pictures before you disassemble. Here's a shot of the old capacitors in place. Notice how a ground wire was sent down to the first wafer to ground both that small 47pf cap and the large .22uf cap laying flat.
It just so happens that the tab for 2200pf cap is next. The short leads on the Wima cap were more than long enough to stretch to both terminals. The two small capacitors don't touch either!
...and now good as new and ready to go back home
Here's a shot of the DC Balance and Low Frequency adjustment area.
With the Preamplifier board bolted back in place, the soldering of the connections begin. Look at this route in and out of the board of these resistors and capacitors! Many pictures and tags get it back together right
There are only two resistors inside of this oscilloscope that are required to be a matched pair, R320 and R401 (1 MOhm 1% type). The original resistors measured 1.0144 and 1.0015 MOhm. Here are the new Dale .1% resistors installed. They
both measure 1.0006 MOhm
The wire connections to the preamplifier board are next and the shields follow. Also, I believe the original wire wrapping had shrunk over time. It appears to have been some sort of plastic cord. The wrapping I'm doing isn't choking-tight
The shields are back in and so is the calibrator, but get this, C102 is the big capacitor in the middle. The old capacitor was an 8uf axial that was strapped-in and grounded over to one of the pots. I was able to just fold back up one of the ground loops around V102 since the new cap is a radial type. I put a small ball of Butyl under it to keep it lifted. I used a 10uf 450V Nichicon UPW cap because it measured 9uf on the Sencore. Capacitor C102 is listed as a -20%/+50% 8uf 450V in the parts legend. And on a side note, the Deoxit F5 and D5 sprays really worked wonders on all of the switches and the Allen Bradley pots, even the sealed ones. Super-smooth!
All in all, over 240 resistors and capacitors were replaced
The rear portion of the CRT is also complete. I was able to relocate C407 to the upper rear corner and eliminate a wire runner because the new 6.8uf Nichicon UCA cap is a radial.
The Time/Division switch is also back in place. You can also see the two NOS Allen Bradley 2 Watt resistors on the Intensity and Focus pots. They are two of the only three new Allen Bradley/Ohmite resistors in this machine. They are not 1%, they are nearly spot on. I can only say this, having followed every trace on the schematics and every solder joint in this scope, I'm in awe of the incredible people of Tektronix of that era that built this thing. I hope I've installed everything correctly so far
Well, she's back in one piece!
I installed the HV board and completed the wiring to the capacitors. I then bundled the remaining wires and closed the case. It will be this afternoon that the tubes will be installed and the oscilloscope powered-up on the Variac
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